Ergonomics in Construction: Where Does it Hurt?

Summary Statement

Interviews conducted with workers using a structured questionnaire and a graphic inquiry determined that the hands, feet and lower back are mostly used; the lower and upper back hurt most, and climbing and descending, and handling heavy materials predominate among ergonomic problems encountered.
August 2000

Construction requires, inter alia, bending and twisting, working
in awkward or cramped positions, reaching away from the body and overhead,
repetitive movements, handling heavy materials and equipment, use of body
force, exposure to vibration and noise, and climbing and descending.

Interviews conducted with workers using a structured questionnaire and
a graphic inquiry determined, inter alia: the hands, feet and lower back
are mostly used; the lower and upper back hurt most, and climbing and
descending, and handling heavy materials predominate among ergonomic problems
encountered.
Keywords: construction, ergonomics, workers, hurt
LITERATURE SURVEY

Introduction

CPWR – Center for Construction Research and Training (CPWR) (1997) cites statistics provided by the US Bureau
of Labor Statistics. The rate of sprains and strains in construction -
1.8 per 100 full-time equivalent workers - is the second highest of all
industries. Sprains and strains (37%) predominated in terms of the nature
of injuries and illness resulting in days away from work. The rate of
back injuries in construction - 1.2 per 100 full-time equivalent workers
- is the second highest of all industries. The back predominated in terms
of anatomic region affected by non-fatal injuries.

'Problem' occupations

According to Hsiao
& Fosbroke (1997) an analysis of injury data indicates that eleven
occupations are "at increased risk" as they represent 31% of
the workforce, but account for 62% of the overexertion injuries. The occupations
are general workers, carpenters, plumbers, drywall installers, roofers,
electricians, structural metal workers, carpet layers, tile setters, plasterers
and machine operators.

Ergonomic problems

Based upon a score
out of 10, research conducted among six trades in the USA determined the
following to be the top five ergonomic problems: working in the same position
for long periods (5.67); bending or twisting the back in an awkward way
(5.46); working in awkward or cramped positions (5.00); working when injured
or hurt (4.69), and handling heavy materials or equipment (4.63) (Zimmerman
et al., 1997).

Where does it
hurt?

Research conducted
among electricians in the USA determined the following anatomic regions
to be the top five in terms of the frequency they were reported to be
a problem: lower back (66.6%); knee (45.9%); wrist/hand (43.6%); neck
(37.2%), and shoulder (37.1%) (Cook et al., 1997). Other research conducted
among six trades in the USA determined the lower back to predominate in
terms of the anatomic regions where workers experienced a problem, followed
by the knee, wrist/hand, shoulder and neck (Zimmerman et al., 1997).

RESEARCH

Four general contractors
(GCs) facilitated the interviewing of 84 construction workers using a
structured interview. A total of 71 usable questionnaires were analyzed.
Thirteen respondents either did not comply with the 'production' worker
requirement, or were incomplete. Of the 71 respondents included in the
analysis, 46.5% were general workers, 12.7% semi-skilled, 12.7% artisans
(craft workers), 9.9% operators and 8.5% apprentices. The mean age was
36.9 and the median 34 years, the youngest worker being 19 years and the
oldest being 62 years of age. On average the workers had worked 14.1 years
in construction and 8.6 years for their current employer, the median being
11.1 and 5.8 years respectively.

Concreting (57.7%) predominated in terms of the work workers mainly did
or were involved with, followed by formwork (45.1%), excavating (39.4%),
and carpentry (22.5%)

Table 1 presents the top nine of a total of eighteen ergonomic problems
based on the daily, weekly, fortnightly, monthly or non-exposure thereto.
Given the possible range of responses in terms of frequency, an importance
index (II), with a maximum of four and a minimum of zero, was computed
to enable ranking of the problems. With the exception of 'climbing &
descending', most of the top nine ranked problems are cited in international
literature, inter alia, Zimmerman et al. (1997) and Cook et al. (1997).
Climbing and descending has previously been determined to be a problem
in South Africa (Smallwood, 1997).

Given the range of the II, it is notable that all the values in Table
2 are above the midpoint of 2.00, implying that all nine problems can
be regarded as prevalent.

Only 22.9% of respondents indicated that reference was 'always' made to
the correct use of tools/body and position when instruction to execute
a task is given. 58.6% responded in the negative.

Table 2 indicates that the majority of workers identified the various
aspects which 'require attention'.

Workers were requested to graphically indicate the anatomic regions they
mostly use at work, where they have pain and to state when the pain occurs.

Table 1Top nine ranked 'ergonomic' problems

Problem

Ranking

II

Climbing
& descending

1

3.23

Handling
heavy materials

2

3.00

Repetitive
movements

3

2.97

Handling
heavy equipment

4

2.87

Use
of body force

5

2.77

Exposure
to noise

6

2.65

Bending
or twisting the back

7

2.38

Staying
in the same position

8

2.30

Working
in awkward positions

9

2.30

Tabel 2'Ergonomic' aspects which require attention

Aspect

Yes
response (%)

Materials
handling

92.6

Materials
storage

90.4

Working
platforms

88.5

Means
of ascending/descending

84.6

Housekeeping

84.6

Walkways

82.7

Mechanization

73.1

Circulation
roads

67.3

Circulation
paths

65.4

Table 3 presents
the top nine of a total of eighteen anatomic regions in terms of use,
the percentage respondents who experienced pain when using a particular
anatomic region, and the percentage respondents who experienced pain in
a particular anatomic region irrespective of its use. Hands

(93%) predominated in terms of the anatomic regions mostly used, followed
by the feet (78.9%) and lower back (66.2%). Knees (52.1%) and shoulders
(40.8%) were used relatively frequently. The upper back (78.6%) and the
lower back (66%) predominated in terms of percentage of the anatomic regions
which hurt of those mostly used. The lower back (43.7%) predominated in
terms of the anatomic regions which pain, irrespective of use.

Table 3Anatomic regions used and frequency of pain

Part

Use
(%)

Pains/Use
(%)

Pains
irrespective (%)

Hands

93.0

9.1

8.5

Feet

78.9

8.9

7.0

Lower
Back

66.2

66.0

43.7

Knees

52.1

13.5

7.0

Shoulders

40.8

34.5

14.1

Lower
Legs

31.0

22.7

7.0

Neck

26.8

31.6

8.5

Elbows

25.4

5.6

1.4

Upper
Back

19.7

78.6

15.5

CONCLUSIONS

Sprains and strains
predominate in terms of the nature of injuries.

The hands, feet and lower back predominate in terms of the anatomic regions
mostly used, and the lower back in terms of the anatomic region which
hurts most frequently.

The 'ergonomic' problems stem from the nature of the construction process,
inter alia, heavy materials and equipment, unit materials, minimal pre-fabrication
and pre-assembly, constricted work areas and insufficient mechanization.

RECOMMENDATIONS

Constructability
reviews conducted during the design process should address ergonomics.

Design and details should be simple and should complement the use of system
formwork, prefabrication, pre-assembly and mechanization do reduce the
effects of various ergonomic problems.